A great variety of packages have been described which are suitable for packaging granular or liquid detergent. A constant preoccupation of detergent manufacturers is to provide packaged goods which are convenient to handle and in particular to store. This requirement includes the possibility to stack packages so that minimum ground space is required.
Granular laundry detergents are known to be packed into flexible pouches. The flexible pouches are such that they are not able to carry any load in an assembly when single or grouped flexible pouches are stacked one over another in the assembly during storing and transportation of the flexible pouches. The load of the stacked assembly is immediately transferred to the contained detergent. It has now been found that certain type of packaged granular or powdered detergents are not able to carry the load and sustain the weight of other packaged granular or powdered detergent when the packaged detegents are stacked in an assembly. Indeed, it is known that certain types of granular detergent "cakes". To "cake" means in the following that the granular or powdered detergent sticks or aggregates together forming lumps when put under a compression force, like a top load. The caking may be such that the detergent aggregates into one insoluble block. The "caking" of a detergent may adversely affect the washing properties of the detergent itself.
The so called "cake strength" is a measure of the caking of a granular or powdered detergent. The "cake strength" is defined to be the force needed to disaggregate a caked detergent. This means that a lower cake strength results in less caking of the detergent. For example, a cake strength of 0 g/cm.sup.2 means that the detergent does not cake. The cake strength of a granular or powdered detergent varies with the composition or manufacturing method of the detergent itself. Therefore, especially when the pouches are filled with granular or powdered detergent susceptible to caking, it is important to take care that the weight or load from the stacked assembly is not carried by the detergent.
To avoid caking of the granular or powdered detergent, the filled flexible pouches are usually combined into a shipping unit which is formed by a high strength outer case. This outer case is able to support the stacking of several shipping units in an assembly. This also means that only the outer case and not the filled pouches combined into these outer cases carry the weight or support the compression force from the stacked assembly. This is certainly one way to avoid caking of the granular or powdered detergent. However, the manufacturing cost of such a packaging assembly is relatively high. Furthermore, the use of the above mentioned outer cases increases the waste packaging materials. Indeed, the outer cases are usually not reusable after the storing and transportation of the flexible pouches. Therefore, the manufacturers of detergent compositions are in need to reduce the costs of the packaging and to reduce the waste packaging materials necessary for handling, storing and transportation of detergent filled in flexible pouches.
It is therefore an object of the present invention to provide a shipping unit of flexible pouches, the flexible pouches being filled with granular or powdered detergent less susceptible to caking when stacking other flexible pouches one over another, and without the need to combine these filled, flexible pouches into outer cases which carry the compression force from the stacked assembly.